Conventional hair dyeing practice involves either the diffusion of a dye into the hair (temporary or semi-permanent coloring) or a chemical reaction between two (or more) organic compounds within the hair fiber to develop a new and larger colored material. While the former method gives poorly lasting results, the latter process yields more permanent and durable dyeings. Unfortunately, this second type of hair dyeing typically requires a strong oxidant such as hydrogen peroxide, which can lead to substantial hair damage.
It has long been the aim of cosmetic chemists and hair colorists to combine the benefits of both methods into a single product. That is, to have a long lasting dye formed in the hair without the concurrent damage associated with oxidative dyeing.
Isatin has been claimed as a direct hair dye, alone or in combination with quinone dyes and involving no chemical reaction (U.K. Patent application GB 2 181 750A). The isatin is unchanged in the process and only dyes yellow.
Another isatin claimed as useful in hair coloring (German Offen. 2 716 671) is diaminoisatin for use in oxidative dyeing. This compound can only be used in the presence of a strong oxidant that causes coupling with a 1,4-disubstituted benzene intermediate to produce color.
Certain derivatives of isatin have been taught in the literature. U.S. Pat. No. 3,374,262 to Seefelder, et al. and U.S. Pat. No. 3,665,029 to Boerth show the production of ortho-aminobenzonitriles by the thermal decomposition of isatin-beta-oximine. The nitriles are described as intermediates and starting materials for dyes.
U.S. Pat. No. 3,558,646 to Buderlein, describes the production of 2- oxo-3-indolinylidene hydrazides as anti-convulsant and inflammatory drugs.
None of these disclosures describe the use of 3-arylimino-indoline-2-ones for coloring keratinaceous fibers, specifically human hair.
The actual materials used in this invention, 3-arylimino-indoline-2-ones, are described in CA79:65375b, CA81:2928e, CA75:117655g; J. Heterocyclic Chem., Vol. 6, p. 125 (1969), Vol. 8, p. 473 (1971) and Vol. 24, p. 1637 (1981); and Heterocyclic Compounds, p. 218 ff (Elderfield, ed., 1952). Notably, in each and every description there is no mention of the dyeing capabilities of these compounds. Also, the novelty of the instant invention, the formation of the dyes by the catalytic action of hair has been heretofore unknown.